Various types of electrical signal filters are used in the CATV industry for controlling, on a frequency basis, the propagation of signals through a cable line. In order to reduce production costs and increase manufacturing efficiency, constant strides have been made toward producing electrical signal filters that can be easily assembled by eliminating more costly manufacturing steps, such as precision soldering. Moreover, in an effort to reduce the labor intensive nature of the manufacturing process, focus has also shifted toward producing electrical signal filters using automated manufacturing processes, such as Z-axis manufacturing techniques.
Examples of electrical signal filters that can be assembled, at least in part, using automated Z-axis manufacturing are disclosed in U.S. Pat. No. 6,429,754, issued Aug. 6, 2002, U.S. patent application Ser. No. 10/187,455, filed Jul. 1, 2002, now U.S. Pat. No. 6,647,342, and U.S. patent application Ser. No. 10/329,055, filed Dec. 24, 2002, now U.S. Pat. No. 6,791,436, each assigned to Eagle Comtronics, Inc., the entireties of which are incorporated herein by reference.
The '455 Application and the '055 Application describe a split filter housing that can be vertically assembled using Z-axis assembly methods. The electrical signal filter includes an elongate lower filter housing member and an elongate upper filter housing member that abuts the lower filter housing member at a junction between the lower side surfaces of the upper filter housing member and the upper side surfaces of the lower filter housing member to define an internal filter cavity. Substantially cylindrical (i.e., round in cross-section) ground posts extend upwardly from the inner surface of the lower filter housing member in a direction substantially perpendicular to the longitudinal direction in which the lower and upper filter housing members each extend (e.g., the axial direction of the filter housing members). A circuit board positioned within the filter cavity includes ground holes that are through-plated with a conductive plating material.
The circuit board is placed within the lower filter housing member in the Z-axis manufacturing direction such that ground pins extending from the uppermost end of the ground posts pass through corresponding ground holes and extend above the upper surface of the circuit board. Once the circuit board is properly positioned on the ground posts, the tip portion of ground pin is peened over to form a solderless mechanical and electrical contact between the ground post and the plated ground hole in the circuit board. In this case, the ground pin must be malleable enough to form a good mechanical and electrical contact with the upper surface of the plating after peening.
As the '455 and the '055 Applications describe, the ground pins can also include a recess extending a distance vertically into the ground pins to a position slightly below the upper surface of circuit board to insure that the peened tip portion of the ground pins make good mechanical and electrical contact with the top of the plating material extending out of the ground holes in the circuit board. The recesses in the ground pins assist in the mechanical deformation of the tip portion of the ground pins by allowing the ground pins to break at certain points, depending on the particular shapes of the ground pins and recesses, so that segments of the ground pins will be pressed outwardly and downwardly against the top of the plated ground hole during the peening operation. The recesses in the ground pins can be formed into a variety of different shapes, such as a cross, a Y-shape or an X-shape, to assist deformation during peening and achieve the desired mechanical and electrical connection between the top of the plated ground hole and the deformed (peened) end of the ground pin.
Although the split filter housing described above represents a step in a direction toward realizing automated Z-axis assembly and solderless manufacturing, room for improvement remains. That is, it would be desirable to provide an electrical signal filter that can be assembled using automated Z-axis manufacturing techniques and that further eliminates the need for peening the ground pins to make the solderless connection with the circuit board.